While installing a file, the pop up with the fake flash player downloaded a dmg to my computer. Because I was already downloading something else and expecting to find it in my downloads I accidentally opened the dmg file. At this point I knew this was not the software I wished to download so I closed the window. The installer might have been left open for several hours past that until I ejected it and deleted it however. So I opened the dmg file and left it open for a while but I didn’t install anything nor run it. Am I good? Is there anyway to be sure?